Control valve for dual independently operable braking systems



Feb.'6, 1962 J. LARSEN EI'AL 3,019,816

CONTROL VALVE FOR DUAL INDEPENDENTLY OPERABLE BRAKING SYSTEMS OriginalFiled Dec. 30, 1957 INVENTORS RICHARD L. LEW/5'. LESTER J. LARSEIV.

2 Sheets-Sheet 1 Feb. 6, 1962 L. J. LARSEN EIAL 3,019,816

CONTROL VALVE FOR DUAL INDEPENDENTLY OPERABLE BRAKING SYSTEMS OriginalFiled Dec. 30, 1957 2 Sheets-Sheet 2 7 6 I B 6 66 I/ 1 o o /0- E h I anINVENTORS RICHARD L. LEWIS. LESTER u. LA/RSEAI.

" nited States Lester J. Larsen and Richard L. Lewis, St. Joseph, Mich,assiguors to The Bendix Corporation, a corporation of DelawareContinuation of abandoned application Ser. No. 705,921,

Dec. 30, 1957. This application Mar. 23, 1960, Ser- No. 18,221

3 Claims. (Cl. 137-621) The present invention relates to a type ofcontrol valve which can be used to independently operate two separatesystems; and more particularly to a valve of the above described typehaving but a single modulating valve to achieve pressure modulation ineach of the two independently actuated systems. This is a continuationapplication ofmy copending application Serial No. 705,921 filed December30, 1957, now abandoned. 7

An object of the present invention is the provision of a new andimproved valve of the above described type which is simple and rugged inits construction, is smooth and etficlent in its operation and which canmodulate pressure in one of the systems throughout an appreciable rangewithout affecting the pressure inthe other of the actuated systems.

A further object of the invention is the provision of 'a atent new andimproved hydraulic brake valve and the like k which will produce theindependent mechanical actuation of either of two braking systems.

The invention resides in certain constructions, and combinations, andarrangement of parts; and further objects and advantages of theinvention will become apparent to those skilled in the art to which theinvention relates from the following description of the preferredembodiment described with reference to the accompanying drawings forminga part of the specification, in which:

FIGURE 1 is a cross-sectional view of a hydraulic control valve whichwill independently operate either of two mechanically actuated brakesystems and which is taken approximately on the line 1-1 of FIGURE 2;

FIGURE 2 isa cross-sectional view of the valve shown in FIGURE 1 takenapproximately on the line 2-2 of FIGURE 1.

The valve shown in the drawing is intended to independently operate thebrake structures of the two rear wheels of a farm tractor; and isadapted to be controlled or operated by means of two foot pedal levers10 and 12, each of which when depressed will cause the valve to actuateone of the controlled brake structures. The valve generally comprises abody member A having five generally longitudinally extending borestherein-the first and third of which, 14 and 18 respectively, aresubstantially identical and form directing valves for individuallycommunicating pressure with the fourth and fifth bores 20 and 22respectively; and the second bore 16 of which provides a modulatingvalve whose operation will supply a modulated pressure to each of thevalves formed by the first and third bores, 14 and 18 respectively.

The modulating valve C is what is known as an open center valve in whichthe pressure supply to the valve is normally communicated directly to aflow-through port without the producing of any appreciable pressure dropin the valve; and the valve is adapted to throttle the flow between thepressure supply port and the flow-through port when the valve isactuated to supply pressure to its control port. The second bore 16which forms part of the modulating valve is provided with an exhaustport 24, a control port 26, a pressure supply port 28, and a flowthroughport 30, arranged in that order in the sidewalls thereof; and a spool orslide member 32 is positioned in the bore 16 with its lands 34 and 36slidably engaging the.

sidewalls of the bore 16. The first land 34 controls communicationbetween the exhaust port 24 and the control port 2e, and the second land36 controls communication between the pressure supply pout 28 and thecontrol port 26. The land portions 34 and 36 are spaced closer togetherthan are the ports 24 and 28; so that a generally predetermined amountof overlap is provided with respect to portions of the sidewalls of thebore 16 on opposite sides of the control port 26. The spacing of thelands 34 and 36 is such that downward movement of the slide member 32will increase the amount of sidewall overlap between the exhaust port 24and the control port 26 while at the same time decreasing the amount ofsidewall overlap between the control port 26 and the supply port 28.Suflicie'nt clearance is provided between the slide member 32 and itsbore 16 such that a flow of fluid can proceed past the land portions 34and 36, and such that the pressure in its control port 26 may be variedby changing the amounts of sidewall overlap on opposite sides of thecontrol port 26 to simultaneously regulate the pressure drop from thesupply port to the control port and the pressure drop from the controlport to the exhaust port. Extremely smooth control of the pressure inthe control port is effected by this arrangement; and any pressurefluctuations in the pressure supply port 28 are quite effectivelydampened out before reaching the control port 26.

As previously indicated, the modulating valve C is an open center typeof valve in which the pressure fluid enters the port 23 and normallyproceeds directly to the flow-through port 30, and the pressure" inflow-through port 36 will normally vary depending upon the back pressureproduced by any valving etc., which receives its pressure supply fromthe flow-through port 30. When a back pressure is experienced in theflow-through port 39, in ward movement of the slide 32 will cause theland 34 to closeoii the exhaust port 24 from the control port 26 and apressure in the control port 26 will be established depending upon therelative amounts of sidewall overlap of the lands 34 and 36 with respectto the sidewall portions between the ports 24 and 26, and 26 and 28respectively. When the land 36 completely opens the pressure supply port28, thefull pressure existing in the flowthrough port 34 will bedelivered to the control port 25. When very little back pressure isexperienced in flowthrough port 36 continued inward motion of the slidemember 32 will cause the lower edge of theland 36 to approach the bottomedge of the pressure supply port 28 and thereby eflfect a throttlingaction of the pressure supply entering through the supply port 28.

The land 36 is of an axial dimension or width which is less than thewidth of the port 28, so that the top of the land 36 will be open withrespect to the top edge of the port 28 when the bottom edge of the land36 starts a throttling action with respect to the lower edge of the port23. The pressure produced in the pressure supply port28 will thereforebe communicated directly to the control port 26; and the amount ofpressure developed in the port 28 is regulated by varying the clearancebetween the lower edge of the land 36 and thelower edge of the supplyport 28.

trol pressure against the bottom end of the spool 32 pro vides areaction which opposes the actuating movement of the slide member 32 byan amount generally proportional to the output pressure of the valve;and the spool 32 is biased into its normal or deactuated upper positionby a coil spring 44 positioned between the lower end of the slide member32 and a plug 46 which seals off the bottom end of the bore 16.

As previously indicated, the directing valves B and B are similar intheir construction and operation and each receives its pressure supplyfrom the modulating valve C (only one therefore need be described indetail). Corresponding parts of the two valves 13 and B will bedesignated by like reference numerals with the reference numerals forone of the valves being further characterized by having a prime markaflixed thereto. The directing valves B, B have exhaust and control andpressure ports 48, t), and 52 respectively, formed in their sidewalls inthe same order that the corresponding ports of the modulating valve arearranged. The pressure ports 52 and 52' of the directing valves B and B,and the control port 26 of the modulating valve C are convenientlyconnected by a single transverse drilling in the body member A; so thatthe control pressure from the modulating valve C becomes the pressuresupply for each of the modulating valves. The spool or slide members 54and 54 are positioned in the respective bores 14 and 13, and each has apair of lands 56 and 58 which are spaced apart a distance slightly lessthan the spacing of the exhaust port 48 and the pressure port 52. Thelands 56 and 58 are so spaced that inward movement of their spoolmembers 54 and 54, respectively, causes their lands 56 and 56' to firstclose oif communication between the control ports 50 and 50 and theexhaust ports 48 and 48 before the lands 58 and 58 open communicationbetween control ports 50 and 50 and the pressure ports 52 and 52. Theslide members 54 and 54' are also provided with a third land portion 69and 69' to guide the lower end of the slide members 54 and 54 withrespect to the lower end of their respective bores. The spool members 54and 54 are biased upwardly into their normal position by means of coilsprings 62 and 62 positioned between the lower end of the respectiveslide members and the bottom end of their respective bores; and suitableinternal drilled passages 64 and 64' are provided in the slide members54 and 54' to .vent the lower end of the respective bores 14 and 16 withtheir return ports 48 and 48'.

In order to achieve the following described sequential operations thespacing of the lower end of the land 56 with respect to the exhaust port48, when its spool 54 is in its normal position, will preferably be lessthan the spacing between the upper edge of the land 58 and the upperedge of the pressure port 52; which in turn is less than the clearanceprovided between the lower end of the land 34 of the modulating valve Cand the lower end of its exhaust port 24, when the spool 32 of themodulating valve C is likewise in its normal position. The slide member54 of the directing valve B and the slide member 32 of the modulatingvalve C are adapted to be moved inwardly from their normal positions bya crank arm 66 that is suitably journalled in the body member A andwhich in turn is actuated by the brake lever 10. The slide member 54' ofthe modulating valve B, and the slide member 32 of the modulating valveC are adapted to be moved inwardly simultaneously from their normalposition by the crank arm 66', which is likewise suitably journalled inthe body member A and is actuated by the brake pedal lever valve 12. Thenormal upper positions for the slide members 54 and 54 are establishedby their engagement with the cranks 66 and 66 respectively when the topsurface of the cranks have been rotated into engagement with the topcover plate 68. The normal position for the slide member 32 of themodulating valve C is established by the uncompressed condition of arelar 4 tively stiff coil spring 79 suitably positioned between the topend of the slide member '32 and a plunger 72 that is slidably receivedin a counter bore 7 din the upper end of the bore 16, and which plunger'72 engages the under surface of each of the crank arms 66 and 66. 7

When the operator desires to apply the left brake of the tractor, hedepresses the foot pedal lever it} to rock the crank arm 66 downwardly,thereby simultaneously forcing the slide member 54 of the directingvalve B and the plunger 72 of the modulating valve C inwardlySimultaneous inward movement of the slide valve 54 and plunger 72 firstcauses the land 56 of the slide member 54 to close oif exhaustport 48from its control port 5i and thereafter open communication between itscontrol port 50 and its pressure port '52. This takes place prior to thetime that the land 34 of the modulating valve C closes off its exhaustport 24; and upon further downward movement of the crank arm 66, theland 34 begins to overlap with the portion of the sidewalls of the bore16 intermediate exhaust port 24 and control port 26, while at the sametime reducing the amount of overlap between the land 36 and the portionof the sidewalls of the bore 16 between its control port 26 and itspressure supply port 28. When a pressure is available in the supply port28, flow immediately proceeds past the land 36 to the control port 26 tobuild up pressure in the control port 50 of the directing valve B andwill continue until such time as the fluid demand of the system to whichthe control port 59 is connected ceases; whereupon all of the fluidwhich flows past the land 36 must also flow out past the land 34 toestablish a control pressure in the control port 26 depending upon therelative pressure drops across the lands 36 and 34, which in turn isdependent upon their relative sidewall overlaps.

The control pressure in the port 26 is also supplied to the bottom endof the slide member 32 to provide a reaction force which compresses thecoil spring 70; so

that the spool 32 will position itself to provide a pressure in thecontrol port that will be substantially directly proportional to thedownward positioning of the crank arm 66. Downward movement of the crankarm 66 may be i stopped at any time that the desired intensity of brakeapplication is achieved; whereupon the spring 70 permits the slidemember 32 to maintain a substantially constant pressure in the controlport 50 of the directing valve B. When the brake pedal lever 10 is fullydepressed, the plunger 72 will be forced into engagement with the bottomend of the counter bore 74 to thereby limit the amount of force appliedto the coil springs 70 and in turn limit the discharge pressure of themodulating valve C. In the valve shown in the drawing, the coil spring70 is so proportioned with respect to the diameter of the bottom end ofthe slide member 32, such that this will occur at approximately 1600p.s.i. which is somewhat below the setting of the relief valve of thepump which supplies fluid to the pressure supply port 28. A similaroperation for the directing valve B and modulating valve C occurs uponthe depressing of the foot pedal lever 12,.which Will be readilyapparent to those skilled in the art, and so will not be elaboratedupon.

As previously indicated, the modulating valve C is of the open centertype where the fluid pressure supplied to the port 28 is normallycommunicated directly to the flow-through port 30; and in thoseinstances when substantially no back pressure is being held upon theflowthrough port 30, actuation of either of the cranks 66 and 66' doesnot produce pressure flow to the directing valves B or B as previouslyset forth. When a back pressure does not exist in the flow-through port30, it will be necessary to continue the inward movement of theappropriate slide members 54 and 54 and the slide member 32, until suchtime as the lower end of the land 36 approaches the lower edge of thepressure supply port 28. When this occurs, the top edge of the land 36will have opened with respect to the top edge of the pressure supplyport 28; and further inward movement thereafter will decrease theclearance between the lower edge of the land 36 and the lower edge ofthe supply port 28 to increase the amount of back pressure supplied tothe control port 26. This requires that the appropriate foot pedal leverbe depressed slightly further than was necessary to apply the brakeswhen back pressure was being supplied to the flow through port 30; butonce restriction is achieved by the land 36, pressure will be producedin the appropriate control port 50 and 50' in a similar manner to thatpreviously described.

Inasmuch as the crack point of the slide member 32 of the modulatingvalve C takes place, when no back pressure is supplied to theflow-through port 30, at a position wherein the slide member 32 isslightly inwardly from the position at which crack point is achievedwhen back pressure is being supplied to the flow-through port 30;slightly less force will be applied to the coil spring 70 when theplunger 72 abuts the bottom of the counterbore 74. Under such conditionsthe maximum pressure produced by the valve will be slightly less thanthe 1600 p.s.i. pressure previously described for the condition where aback pressure in excess of this amount was being held against theflow-through port 30. It will thus be seen that the maximum backpressure which can be produced by the valve of the present inventionwill at times be below a predetermined maximum-which pre determinedmaximum if less than the relief valve setting of the pump connected tothe supply port 28, will prevent the valve from completely shutting offall flow through the flow-through port 30.

The control ports 50 and 50' of the directing valves B and Brespectively may in some instances be communicated by suitable conduitsto remotely located brake actuated hydraulic cylinders; but in the caseof some types of farm machinery will preferably be communicated throughinternal passages in the body member A to the bores 20 and 22respectively, which contain hydraulic pistons 76 and 76' respectively,and by means of which, mechanical forces can be implemented directlyfrom the body member A. Suitable O-ring seals 78 and 78' are provided inthe bottom end of the bores 20 and 22 respectively; and each of thepistons 76 and 76' is provided with a clevis arrangement for theattachment to independently operable brake actuating mechanisms. Bymeans of such an arrangement a substantial simplification of brakeactuating mechanism is produced having no external conduits that can beruptured or damaged through usage.

While the invention has been described in considerable detail, I do notwish to be limited to the particular construction shown and described;and it is my intention to cover hereby all novel adaptations,modifications and arrangements thereof which come within the pratice ofthose skilled in the art to which the invention relates and which comeswithin the scope of the following claims.

We claim: 1. In a control wave for controlling pressure in two separatesystems: a valve body member having two motor ports whose pressuresupply is to be modulated, first and second individual flow directingvalve chambers each of which chambers has an exhaust port, a controlport communicating with one of said motor ports, and a pressure port;first and second control members for respective ones of said first andsecond valves each of which when moved in one direction closes off itsexhaust port from its control port and thereafter opens communicationbetween its control port and its pressure port; a modulating valvecomprising a longitudinally extending bore in said body member having anexhaust port, a control port communicating with said pressure ports, anda pressure supply port arranged in that order in the sidewalls of saidbore; a third control member in said bore having a pair of lands one ofwhich in the normal position of the third control member provides amaximum sidewall overlap between its supply and control ports while theother is open with respect to its exhaust port, and which when actuatedprovides increasing sidewall overlap between its control and exhaustports while decreasing sidewall overlap between its control and supplyports; a first actuating means which simultaneously moves said first andthird control members in their actuating directions; and a secondactuating means which simultaueously'moves said second and third controlmembers in their actuating directions; said first and second directingvalves and said modulating valve being so constructed and arranged withrespect to each other to ensure upon each operation of each of saidactuating means that the pressure ports of said directing valves arenormally closed and are opened at a time when a pressure, relatively lowto the maximum pressure to be supplied to said pressure supply port, issupplied said pressure ports by said modulating valve.

2. In a hydraulic brake actuating system for farm machinery and thelike: a body member having first, second and third bores therein, saidfirst and third bores each having an exhaust, a motor port, and apressure port spaced apart in that order in the sidewalls thereof fromone surface of said body member, said second bore having an exhaustport, a control port communicating with said pressure ports, and apressure supply port spaced apart in that order in the sidewalls thereoffrom said surface; first and third slide members in respective ones ofsaid first and third bores each having a pair of lands one of which inthe normal position of the slide member provides sidewall overlapbetween its pressure and motor ports while the other is open withrespect to its exhaust port, and which when actuated opens its pressureport and provides sidewall overlap between its motor and exhaust ports;a second slide member located in said second bore and having a pair oflands one of which in the normal position of the slide member provides amaximum sidewall overlap between its supply and control ports while theother is open with respect to its exhaust port, and which when actuatedprovides increasing sidewall overlap between its control and exhaustports while decreasing sidewall overlap between its control and supplyports; a first actuating means which simultaneously actuates said firstand second slide members; and a second actuating means whichsimultaneously actuates said second and third slide members; said portsbeing so constructed and arranged that said actuating means when movedfrom their normal positions first opens up its respective pressure portbefore appreciable pressure is built up in its respective pressure portby its movement of said second slide member.

3. In a hydraulic brake actuating system for farm machinery and thelike: a body member having first, second and third generally parallelbores therein, said first and third bores each having an exhaust, amotor port, and a pressure port spaced apart in that order in thesidewalls thereof from one surface of said body member, said second borealso having an exhaust port, a control port communicating with saidpressure ports, and a pressure supply port spaced apart in that order inthe side walls thereof from said surface; first and third slide membersin respective ones of said first and third bores each having a pair oflands one of which in the normal position of the slide member providessidewall overlap between its pressure and motor ports, while the otheris open with respect to its exhaust port, and which when moved inwardlyfrom said surface opens its pressure port and provides sidewall overlapbetween its motor and exhaust ports; a second slide member located insaid second bore and having a pair of lands one of which in the normalposition of the slide member provides a maximum sidewall overlap betweenits supply and control ports while the other is open with respect to itsexhaust port, and which when moved inwardly from said surface providesincreasing sidewall overlap between its control and exhaust ports whiledecreasing sidewall overlap be- 8 tween its control and supply ports; afirst actuating means for simultaneously moving said first and secondslide members inwardly; and a second actuating means for simultaneouslymoving said second and third slide members inwardly; said ports being sospaced that said actuating means when moved from their normal positionsfirst opens up its respective pressure port before any substantialclosing of the exhaust port in said second bore is efiected by saidsecond slide member. 7

References Cited in the file of this patent

